Theme
WATER
CSI 020 Nutrients in freshwaters
groundwater a clearly expressed increasing trend which is still
Key message
within the legally required limit values.
During the period 2000-2005, phosphorus concentrations in
Considering the content of nutrients in freshwaters, the sta-
lakes and rivers showed, with some fluctuations, no noticeable
te of the Croatian rivers is generally good.
trends. Nitrate concentration values for lakes do not show any
noticeable trend, while values for in lakes show mild and for
Figure 1. Median of annual average concentration values of nitrates and orthophosphates for rivers in Croatia, 20002005
µg P/L
50
mg NO3 /L
5.0
45
4.5
40
4.0
35
3.5
30
3.0
25
2.5
20
2.0
15
1.5
10
1.0
5
0.5
0
2000.
46
3.5
*
**
2001.
34
3.5
2002.
35
4.6
2003.
36
4.0
2004.
39
4.7
2005.
44
4.6
* Median of annual average concentrations of orthophosphates
(μg P/L) in rivers
** Median of annual average concentrations of nitrates
(mg NO3/L) in rivers
0.0
Source: Croatian Waters< Analysis: Croatian Environment Agency
Figure 2. Median of annual average concentration values of total phosphorus and nitrates in lakes in Croatia, 2000-2005
µg P/L
mg NO3 /L
60
3,0
50
2,5
40
2,0
30
1,5
20
1,0
10
0,5
0
***
****
2000.
2001.
2002.
2003.
2004.
2005.
34
2,2
54
2,3
55
2,6
32
2,3
30
2,8
30
1,9
*** Median of annual average concentrations of overall phosphorus
(μg P/L) in lakes
**** Median of annual average concentrations of overall nitrates
(mg NO3/L) in lakes
0,0
Source: Croatian waters; Analysis: Croatian Environment Agency
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Figure 3. Median of annual average concentration values of nitrates in groundwater in Croatia, 2000-2005
mg NO3 /L
10,0
9,0
8,0
7,0
6,0
***** Median of annual average concentrations of nitrates
(mg NO3/L) in groundwater
5,0
4,0
3,0
2,0
1,0
0,0
*****
2000.
5,0
2001.
6,3
2002.
7,4
2003.
5,6
2004.
8,1
2005.
9,1
Source: Croatian waters; Analysis: Croatian Environment Agency
Results and assessment
cal water supply systems, private wells, etc.) which are not covered
Policy relevance
by the quality control system, it is highly important to observe the
Monitoring of surface water quality in Croatia is being carried
trends of nitrate values because it has been proven that increased ni-
out according to the Water act (OG 107/95, 150/05), National Water
trate values are harmful for human health, especially that of infants.
Protection Plan (OG 8/99), and Regulation on Water Classification
It is necessary to keep in mind the long time offset in nitrate
(OG 77/98). This report encompasses all the monitoring stations
seepage from the surface to the groundwater, which depends upon
from the national monitoring program. Quality of groundwater
the type of soil and geomorphology and can take up to 40 years.
used for public water supply has been monitored according to
the Rules on Drinking Water Quality (OG 182/04).
Phosphorus concentrations for lakes and rivers in Croatia with
value fluctuations do not show any noticeable trend.
Increased concentrations of nitrate and phosphorus compounds in water are consequence of industrial and urban wastewa-
Assessment
Although the surface water quality has been systematically
ter pollution and elutriation of nutrients from agricultural surfaces.
monitored since the 1970s, with upgrading of the monitoring sys-
Increased concentrations of phosphorus are mainly a consequence
tem (higher frequency, method standardization) the year 2000 has
of urban wastewater pollution while the increased concentrations
been defined as a baseline year for the water quality assessment
of nitrate are a consequence of elutriation of nutrients from agri-
in Croatia. The national classification results in waters being as-
cultural surfaces.
sessed as falling in one of 5 quality classes, where quality class
Nitrate and phosphorus are nutrients necessary for the growth
I is the best and quality class V the worst grade. Water quality
of algae and other freshwater plants. Increase in quantities of nitrate
assessment is carried out separately, according to the groups of
and phosphorus in freshwaters could cause eutrophication resulting
parameters: oxygen regime, nutrients, and microbiological and
in a number of adverse changes decreasing biodiversity of aquatic
biological parameters.
ecosystems and degradation of water quality thus limiting the pos-
During the five-year period under consideration, nitrate con-
sibility of its use for different purposes (drinking, bathing etc.).
centrations show a slight increase in values in rivers and groundwater, while the values for lakes, with fluctuations, show no noticeable trend. Nitrate concentrations recorded for groundwater
(5-9 mg NO3/L) are significantly below the maximum allowed
concentrations, which is s 50 mg NO3/L for drinking water (Rules
on Drinking Water Quality, OG 182/04). Considering that 90% of
drinking water supplied in Croatia tapped groundwater and that
part of population (about 24%) is connected to private sources (lo-
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Table 1. Number of monitoring stations for the monitoring of lakes, rivers and groundwater quality in Croatia
Number of monitoring stations –
Number of monitoring stations –
Number of monitoring stations –
groundwater
lakes
rivers
2000
135
42
195
2001
124
42
215
2002
140
43
221
2003
160
43
208
2004
162
43
252
2005
160
43
255
Year
Source: Croatian Waters
Analysis: Croatian Environment Agency
Metadata
Legal bases for the indicator:
Water Act ( OG 107/95, 150/05)
Quality information (at data level):
Data are available from the Croatian Waters, which is under
Regulation on Water Classification (OG 77/98)
no obligation to analyse testing results in this way. Only the
National Water Protection Plan (OG 8/99)
surface water quality assessment is requested. Quality of groun-
Rules on Drinking Water Quality (OG 182/04)
dwater tapped for public water supply is monitored according
to the requirement of the Rules on Drinking Water Quality (OG
Data source (s):
182/04).
Hrvatske Vode (Croatian Waters)
Data availability:
Geographical coverage: national
For development of this indicator, all monitoring stations
from the national monitoring system monitoring river quality
Temporal coverage: 2000-2005
have been taken into consideration (Table 1). Croatian Waters are
required to submit annual reports on the results of water quality
Methodology and frequency of data collection:
Methodology and frequency are stipulated by the national
legislation. Measurements are done at the monitoring stations
analysis in Croatia, according to the program of the Croatian
Waters approved by the Ministry of Agriculture, Forestry and
Water Management.
within the national monitoring system.
Methodology of data manipulation (measurements):
Calculations are based on mean annual values determined
at the monitoring stations. Data for a period of one year are
analysed, and the parameter measurement frequency is 6 - 26
times a year.
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